The present invention relates to sorption systems, and more particularly to processes and devices for conveying the boilable liquids used therein.
The invention relates to a process and a device for conveying boilable liquids in which process or in which device the required delivery pressure is generated by alternately changing the boiling pressure of a boilable liquid from a low starting point to a boiling pressure, increased by the desired increase in pressure by an external heat input, and then the original state is reproduced by reducing the pressure to the low boiling pressure by dissipating the heat externally, whereby the boilable liquid is subjected to a work-performing cyclic process in the wet steam region, which process comprises a reduction in pressure by means of dissipation of heat, compression by means of dissipating heat to a low temperature level, increase in pressure by means of a heat input, as well as an expansion to a higher temperature level through heat input, in particular in a sorption system (absorption refrigerating machine, absorption heat pump or absorption heat transformer and resorption refrigerating machine, resorption heat pump or resorption transformer).
The solution pump of a sorption system causes significant problems due to its construction. The pressure difference to be bridged is dependent on the pairs of substances comprising the refrigerant and solvent that are used. A frequently used pair of substances is NH.sub.3 and H.sub.2 O in which pressure differences of 20 bar and more can occur. The problems that arise in this case and that are similar in the case of many other pairs of substances are low efficiency and cavitation problems, as well as the expulsion of frequently environmentally harmful and/or poisonous refrigerant. Furthermore, the cost of these components, in particular in the case of large refrigeration and heat installations, when measured against the costs of the entire system, can be disproportionately high.
A process for operating absorption heat pumps is known from DD 219 060 wherein to save electric energy a solution pump, designed as a membrane, with a thermal drive part is used that comprises a closed vessel filled with a two substance mixture containing ammonia and water, in which process there is a temperature changer that is driven periodically with cold steam from the evaporator and with a warm medium from the circulating heat pump.
This kind of device requires that two heat exchangers be periodically heated and cooled. Thus, a slow and inefficient procedure is unavoidable because from time to time the entire heating and the entire cooling heat exchange system must be heated up or cooled down. Furthermore, due to the mandatory membrane that becomes stressed from continuous duty, its replacement is periodically necessary, which requires that the entire system be dismantled.